Yes , it can be a little confusing for the non technical computer user.
Screen resolution is effectively the image size displayed by the monitor.
Resolution can be changed in the control panel in windows. Depending on the version of windows the button in control panel will be labeled display or Nvidia , Nvidia being the option in Vista onwards , well , I'm pretty sure it wasn't Nvidia in W98.
If you are having the problem of image exceeding the width of the screen then select a higher resolution , but note , on older , cathode ray tube monitors displaying a higher resolution than the monitor can cope with may damage it eventually. Flat screen / LCD / TFT monitors are not affected by resolution. Actually , if you are still using a CRT monitor , do yourself a favour and upgrade to an LCD type , they are pretty cheap now and you won't believe the improvement !!